One test of truth is history. If it hapened and was recorded then it is true. So go back into history to review the points of beginning for the Catholic church. Does it have a history? Who started it? When did it start? Is there a lineage from today’s Pope all the way back to Jesus - that is unbroken and continuous - not adultered by man?
Another test of truth is longevity. The truth cannot be destroyed. It can be spun into nonesense. It can be colored with lies and falshoods. It can be denied and attacked, but if it is true, it will not be destroyed. It will continue because the truth attracts people of reason. They recognize it and desire it. So, how long has Catholicism been around. Has it been lied about, attacked, spun into nonesense and yet still is exists?
I would suggest you go to www.salvationhistory.com which is the web site for Scot Hahn and obtain some of his CD’s. He was a protestant minister before converting to the Catholic Faith and he does a remarkable job in explaining Catholicism.